As a Disney passholder who missed the opening day for passholders because I really do not like crowds, I waited until a couple weeks after it was open and then braved the elements and went to Pandora at Animal Kingdom. I strategically planned my visit for the middle of the week on the last week of school in central Florida to try to avoid too high of crowds, and it paid off.
My children and I are huge Avatar fans. We love the nature and environment and idealism of such a place and we couldn't wait to see it! For those of you who want to go, I 100% recommend going. Disney has completely outdone any expectations and created another truly magical place.
Or go there first in the morning and re-visit at night. It is worth seeing in both day and night as the magic comes alive. We entered Pandora at 6pm and stayed through closing and watched as the land lit up and glowed.
The land gets pretty dark and the walkways are not very well lit in order to give the full blacklight effect, so I'd recommend adding some article of clothing to you and your children, like a headband, hat, bracelet, socks or shoes that are white or a bright color that will glow so you can keep a better eye on each other.
Tip... it's summer, it's hot and it's crowded so know that you will face crowds. Plan ahead and get your fast-passes. Animal Kingdom allows up to 3 fast-passes. Unless you are staying at a Disney resort and planned 60 days ahead, it's very unlikely that you will get a fast-pass for the rides in Pandora, Avatar Flight of Passage or Na'vi River Journey. But you can get fast-passes to the other rides in Animal Kingdom so when you have to wait for just 2 rides, it won't seem so bad.
The food at the restaurant, Windtraders, is excellent and offers so many great choices, including real food and real healthy choices. The dessert and the drinks are an added bonus!